Procedure in non woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties

ABSTRACT

Procedure for obtaining non-woven fabrics with acoustic, thermal and filtering properties, obtained with a mechanical carding method or hydroforming and combined by spunlace or punching, and may or may not be reinforced with the aid of a resin polymer, characterized by using a novel mixture of fibers with different denier between 0.01 to 30, as well as fibers that may even be of synthetic, natural and/or mineral origin for acoustic, thermal, filtration, comfort and cleaning applications, for different markets.

TECHNICAL FIELD OF THE INVENTION

The present invention refers to a procedure for manufacturing non-woven fabrics and their products with acoustic, thermal, filtering, comfort and cleaning properties obtained through fiber mixtures, of diverse designs, with similar or different denier or different chemical nature, attached by spunlace or punching with good properties for applications such as acoustic, thermal insulation and with filtering and comfort applications for various industries such as footwear, construction, automotive, filtration, cleaning and preparation.

OBJECT OF THE INVENTION

The object of this invention is to produce, with a novel technique, non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, being lighter or at least the same weight, but more efficient in these properties, as shown below.

BACKGROUND OF THE INVENTION

Several processes have been used for the formation of non-woven fabric such as: punching, spunlace or chemical linking. Document U.S. Pat. No. 4,018,646 discloses the use of bonding as well as carding, pressed by two rollers, thus changing its surface texture, giving a more compact appearance. There are also the examples on document MX1929629, of the instant inventors, dealing with devices that use water pressure and thus facilitating the abutment or bonding with jets of water at high pressure, “spunlace”.

The instant invention achieves novel properties innovating over the prior art, including our patent MX282285, where nonwoven fabrics are obtained by mixing long fibers from 100 mm length to continuous filaments and small fibers from 1 mm to 100 mm by wet or dry means and bonding by a method of punching, spunlace, thermo-bonding, or chemically bond or a combination of nonwoven porous fabric with a porous woven fabric.

Now, this invention innovates by interacting with fiber mixtures ranging from 0.01 denier to 30 denier, designing structures for the formation of cavities that benefit acoustical and thermal properties, as well as the creation of pores for the proper separation of materials that can be filtered on these non-woven fabrics, comfort and particles retention properties are also observed and are used in the cleaning market. This is achieved with mixtures of various denier and lengths.

The present invention is the result of intensive research and development, designing properties that can be applied to achieve functionality with the same or less weight, which translates into lighter constructions, quiet and thermally-insulated spaces, lighter, faster and more quite automobiles for the drivers, more efficient filtration and more thorough cleaning with lighter products, this being accomplished with non-woven fabric obtain with fiber mixtures of different denier ranging from 0.01 up to 30 denier, wherein the extension of properties can be obtained with the aid of a polymeric resin to obtain a final weight between 40 to 2,000 g/m².

The present invention discloses a non-woven fabric made with fibers obtained with polymers of different chemical nature such as: polyester, polyolefins, polyamides, poly (lactic acid), acrylic, polyaramids, cellulose, cotton, rayon, fiberglass, low melting point polymers or any combination thereof maintaining the denier differential from 0.01 up to 30, wherein the extension of properties can be obtained with the aid of a polymeric resin to obtain a final weight between 40 to 2,000 g/m².

An advantage of the products obtained with this invention is that superior acoustic, thermal, filtering, anchoring and comfort properties can be obtained with the same weight and thickness conditions, allowing the reduction of weight. This is due to the adequate integration of components by selecting the correct denier and fibers' nature to obtain a product with improved performance, according to the market requirement.

These materials require acoustic properties with a high absorption coefficient, that indicates the sound absorption level of materials, and especially for compact materials the high losses due to transmission are exploited, that shows the sound levels that are lost when impinging on materials, which is other acoustic property that is improved with this novel non-woven fabric.

In terms of thermal properties, the non-woven fabrics of this invention show a thermal conductivity lower than conventional non-woven fabrics, due to their design since its construction allows a novel structure and distribution of empty spaces and for this reason the thermal conductivities of the air and the fibers are combined contributing to the global thermal conductivity coefficient.

The filtering properties are achieved by providing cavities that allow increasing the capacity and narrow channels for retaining smaller particles, improving the efficiency of the non-woven fabric described herein.

Technical Problem to Solve

This invention relates to a procedure in non-woven fabrics and non-woven fabrics themselves having acoustic, thermal, filtering, comfort and cleaning properties with better performance and efficiency than traditional non-woven fabrics in the same conditions, as well as providing an easy handling unlike fabrics specifically developed to attack each property, in other words, they do not cause damages or risks to humans or to the environment, while handling and functionality.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-section of the non-woven fabric that has acoustic, thermal and filtering properties, in accordance with the present invention.

FIG. 2 shows a cross section of the non-woven fabric of FIG. 1, but with a variation of the invention, an application of polymeric resin to increase performance, promote or expand the properties of the final product.

FIG. 3 shows the acoustics comparative plot of a traditional non-woven fabric with two examples of non-woven fabrics obtained in accordance with the present invention.

FIG. 4 shows a comparative graph of the filtering efficiency among the non-woven fabrics of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Details characteristic of this novel procedure for obtaining nonwoven fabrics with acoustic, thermal, filtering, comfort and cleaning properties are clearly shown in the following description and the accompanying drawings.

The procedure for preparing a non-woven fabric with filtering, acoustic, thermal, comfort and cleaning properties, according to the present invention consists of:

a) Making a non-woven fabric beginning with a veil with the mixing of fibers of different denier, i.e., with a large diameter differential, where the length of the fibers can be equal or different among themselves, using a mechanical carding method or hydroformed or formed with air . . . . b) Once the above described the veil is formed, it is combined by any of the following processes: spunlace, punching, thermal, sweing, chemical and any combination thereof. If the spunlace process is used, it is designed by using hydraulic pressures from 20 up to 400 bars to promote the tying between fibers showing a broad denier differential. If the punching process is used, tying is allowed by a design with optimal densification of the non-woven fabrics. c) Once the fabric is formed, a variation is possible by adding a thermal treatment by contact with a hot surface or in a hot air oven allowing that the non-woven fabric increases its dimensional stability. This treatment will vary depending on the nature of the fibers, i.e., it can be made from 80° C. to 240° C. d) Another variation to the final process involves incorporating a polymer resin. First a suspension of the polymeric resin is prepared selected according to the properties, such as stress resistance, stiffness, touch, surface tension, visual appearance, that are object of this invention, where suspended polymer particles are incorporated into the non-woven fabric when passed altogether through a pair of rollers, forcing to saturate the non-woven fabric. Afterwards, it is dried and finally an optinal additional thermo melting is applied so that the polymer added to the non-woven fabric adquires higher tension resistance.

As used herein, the term non-woven fabric generally includes, but is not limited to: non-woven fabric made of synthetic, natural, mineral and/or thermoplastics fibers, made from polymers such as: polyester, polyolefin, polypropylene, polyamides, poly (lactic acid), acrylic, polyaramids, cellulose, cotton, rayon, fiberglass and low melting point polymers and combinations thereof. In the above-mentioned non-woven fabrics, small fibers with different denier are mixed that can be microfibers from 0.01 denier to 30 denier and having different lengths from 3 mm up to 150 mm or continuous filaments or combinations thereof. In addition, the fibers may also have differences on their cross-sectional geometries. They may be circular, symmetrical or irregular, solid or with internal spaces or combinations thereof. These non-woven fabrics are manufactured by any of the known methods such as: pneumatics, wet and mechanical formation, strengthen this method with methods such as: spunlace, punching, thermal, sewing, chemical and combinations thereof.

It is worth mentioning that fibers having different or the same nature or chemical composition can be used on the same fabric, promoting, according to the case, the biggest differential on denier or the adequate porportion for the specific application.

Throughout this invention the term polymer resin includes, but is not limited to: acrylic resins, polyurethanes, latex, styrene-acrylic, phenolic, epoxy, vinyl and combinations thereof, as well as chlorofluorocarbons, surfactants and organic and inorganic phosphates and combinations thereof, and by using any of the known methods: impregnation with resins having different densities or mixes thereof, are applied directly after forming the non-woven fabric obtained by spunlace or punching for promote or achieving significant properties that are an object of this invention.

Non-woven fabrics may have final weights of 40 g/m² up to 2000 g/m².

As the term differential of denier is used, where the term “denier” is defined as the weight in grams of a continuous filament of 9000 meters of the same diameter, denier is thus, a relationship of diameter and density of the material from which the fiber is obtained. Thus, the difference of denier refers that in the same fabric thin fibers from 0.01 denier and coarse fibres up to 30 denier can be used. This combined with the properties of the materials from which the fibers are obtained, creates structures and design of spaces that break up the sound waves and provides high acoustic absorption. These spaces can also be designed to promote the separation of micrometric particles of air flow, individually or in combination with the processes to obtain products with filtration properties. Also the combination of air inside these cavities and the material from which the fibers are made become two resistors in parallel that achieve the thermal insulation for the non-woven fabrics of this invention.

Referring to the drawings and in particular FIG. 1, it is shown a cross-section of the non-woven fabric with acoustic, thermal and filtering properties where an example of a design with different diameters of the fibers used can be observed, wherein (a) are thin fibers and (b) are thick fibers, that according to the arrangement of these fibers in the non-woven fabric create cavities that vary with the differential of the selected diameters.

In another embodiment of the invention illustrated in FIG. 2, the cross section schematic is shown where (a) are the fine fibers are fine, (b) are the thick fibers and (c) are the tyings reinforced with polymer resin.

FIG. 3 shows an acoustic plot known as “Absorption Coefficient” wherein the x-axis is the frequency in Hertz, a portion where the audible spectrum (20 Hz to 20 kHz) and where the human ear has greater sensitivity (2 kHz to 4 kHz), thus the plot goes from 0 to 5000 Hz. In the y-axis the absorption coefficient of the materials is shown ranging from 0 to 1, where “0” is where the material does not absorb any sound and “1” is where the material absorbs all sound. This graph compares three materials where (I) is a non-woven spunlaced fabric, with a single type of polyester fiber of 3 denier, (II) is a non-woven spunlaced fabric with a mixture of polyester fibers of 1.5 denier and 0.01 denier and (III) is a non-woven spunlaced fabric with a mixture of polyester fibers of 7 denier, polyolefin of 1.5 denier and polyester of 0.01 denier where (II) and (III) are in accordance with the present invention and the three fabrics are made in 200 g/m² in the same spunlace process conditions.

Thus, it can be appreciated from the plot of FIG. 3 how the differential of denier according to the present invention benefits the absorption of sound.

The thermal properties are favoured with the same differential of denier present in the fabrics of FIG. 3, while (I), the non-woven fabric with similar denier polyester fibres, shows a thermal conductivity of 0.29 W/mK (Watts per meter and Kelvin degree), the non-woven fabric (II) shows a thermal conductivity of 0.24 W/mK and the non-woven fabric with the greater differential of denier (III) shows a thermal conductivity of 0.19 W/mK, so the fabric with the greater differential provides greater resistance to heat flow with the same thickness as the other fabrics, since at lower thermal conductivity greater resistance to the flow of heat with the same thickness.

In regards to the filtering properties, the non-woven fabric (I) with the single type of polyester of 3 denier has an average pore diameter of 45 μm, the non-woven fabric (II) with the mixture of polyester fibers of 1.5 denier and 0.01 denier, has an average pore diameter of 26 μm, and the non-woven fabric with higher differential denier (III) with the mixture of 7 denier polyester fibers, polyolefin of 1.5 denier and polyester of 0.01 denier show an average pore diameter of 32 μm, which favors such filtering properties, since a smaller average pore non-woven fabric is selective with smaller diameter particles and the pore size is designed based on the particles to filter. This is clearly seen in the plot of FIG. 4 “Filtration Efficiency”, where the filtration efficiencies are compared, i.e., small pores behave better with the smaller particles, as well as the capture of dust that are favored by the new conditions of the present invention, since the non-woven fabric (I) has a capture of 120 g/m², while the non-woven fabric (II) has a capture of 215 g/m² the non-woven fabric (III) has a capture of 240 g/m², and the efficiency property of the non-woven fabric (III) has a retention of particles between 0.3 and 0.4.

Considering that the above-provided explanation, as well as the figures, broadly describes the procedure using fiber mixtures, some examples of its application are provided below.

Example of Embodiment 1

To manufacture the non-woven fabric with acoustical, thermal, filtering, comfort and cleaning properties, polyester fibres of 1.5 denier by 51 mm long and polyester fibres of 0.01 denier by 51 mm long are mixed and formed first with a mechanical carding method.

Once the veil is formed, it is combined by a spunlace process with hydraulic pressures going from high to low to favour the tying between fibers that show a large differential of denier.

Finally, the non-woven fabric is dried using a hot air process or by contacting with hot surfaces.

This example used the additional polymeric resin reinforcement section, so that when the non-woven fabric is obtained a base water solution having suspended acrylic particles is applied and is dosed in a pair of rollers, forcing the solution to saturate the non-woven fabric. Then, it is dried and finally an additional thermo-melting is provided so that the non-woven fabric acquires greater resistance to stress.

So the fabric of 200 g/m² has the following relationship:

1) Fibres of 1 denier on average by 51 mm long . . . 90%. 2) Acrylic resin . . . 10%.

The acoustic properties of this example of the embodiment 1 are expressed in the non-woven fabric (II) of FIG. 3.

Example of Embodiment 2

In this example of making a non-woven fabric spunlaced with acoustic, thermal, filtering, comfort and cleaning properties, polyester fibres of 7 denier by 51 mm long, polyolefin fibers of 1.5 denier and polyester fibres of 0.01 denier by 51 mm long are mixed with a conventional mechanical carding method of.

Once the veil is formed, it is combined by a conventional spunlace process with hydraulic pressures going from high to low to favour the tying between fibers that show a large differential of denier.

Finally, the non-woven fabric is dried with hot air or by contact on hot surfaces and finally an additional heat treatment is applied so that the non-woven fabric acquires greater resistance to stress.

So the fabric of 200 g/m² has the following relationship:

1) Fiber of 2.5 denier on average . . . 100%.

The acoustic properties of this example of embodiment 2 are expressed in the non-woven fabric (III) of FIG. 3, where the best acoustic properties are observed due to the the differential of denier and nature of fibers. 

Having described the invention above, the following is claimed as property:
 1. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, characterized of the steps: a) Making a non-woven fabric with a mixture of fibers having a broad differential of denier by any of the methods such as: pneumatics formation, wet or mechanical, combined with processes like spunlace, punching, heat, sewing, chemical or combinations thereof. b) Applying heat to the product derived from the process a) via wet or spunlace for drying in a process by hot air or by contacting with hot surfaces between 100° C. and 240° C. and provide an additional heat treatment if necessary between 80° C. and 250° C. to the product derived from the process a). c) Adding a polymer resin, as an optional variation after the process a) and b), preparing a suspension of a water-based polymer resin to favour the properties of strength, rigidity, stability, forming, acoustic absorption, surface tension, efficiency and uptake in filtration and thermal resistance where the suspended polymer particles are incorporated into the non-woven fabric when altogether are passed through a pair of rollers. d) The non-woven fabric impregnated with the polymer resin obtained in the process c) is dried by hot air or by contact with hot surfaces between 100° C. and 240° C., providing a thermal treatment between 100° C. and 250° C., for an additional thermo-bonding so that the polymer added to the non-woven fabric acquire stability and develop the properties described in the process c). e) In a further variation to the processes a) and b) with the presence of low melting point fibers a thermal treatment is applied between 100° C. and 200° C. to activate these fibers and thus obtain a thermo-bonding, providing dimensional stability, durability and strengthen the structure.
 2. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1, characterized because the fiber mixture includes a differential of denier between 0.01 denier and 30 denier, as well as its cross-sectional geometry can be circular, symmetrical or irregular solid or with internal spaces or combination thereof.
 3. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1, characterized because the fiber mixture includes small fibers ranging from 3 mm to 150 mm long and up to continuous filaments.
 4. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1, characterized because the combination of fibers includes fibers that are usual, synthetic, natural, mineral and thermoplastic, as polyester, polyolefin, polypropylene, polyamides, poly (lactic acid), acrylic, polyaramids, cellulose, cotton, rayon, fiberglass and low melting point fibers (of 110° C. to 200° C.), and these polymers are included in homopolymers or combinations thereof.
 5. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1, characterized because the mixture of fibers includes combinations of denier, long, geometry and groups of fiber based on their origin, the latter also according to claims 2, 3 and
 4. 6. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1 subsection c), characterized because the polymer resin is found within the group comprising acrylic resins, polyurethanes, latex, styrene-acrylics, phenolic, vinyl or epoxy, as well as chlorofluorocarbons, surfactants and organic and inorganic phosphates and combinations thereof.
 7. A process for obtaining non-woven fabrics with acoustic, thermal, filtering, comfort and cleaning properties, according to claim 1, characterized because the weight of the non-woven fabric obtained in accordance with the claims 1-6 is in the range of 40 to 2000 g/m².
 8. Non-woven fabrics, products, derivatives and their applications, obtained using the procedure in accordance with claims 1 to 7, with acoustic, thermal, filtering, comfort and cleaning properties as resistance, rigidity, stability, forming, acoustic absorption, surface tension, efficiency and uptake in filtration and heat resistance, for the markets of the industry such as shoe, construction, automotive, filtration, clothing and cleaning. 